Dyslexia and Developmental Language Disorder: comorbid disorders with distinct effects on reading comprehension

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BACKGROUND: Reading comprehension draws on both decoding and linguistic comprehension, and poor reading comprehension can be the consequence of a deficit in either of these skills.

METHODS: Using outcome data from the longitudinal Wellcome Language and Reading Project, we identified three groups of children at age 8 years: children with dyslexia (N = 21) who had deficits in decoding but not oral language, children with Developmental Language Disorder (DLD; N = 38) whose decoding skills were in the normal range, and children who met criteria for both dyslexia and DLD (N = 29).

RESULTS: All three groups had reading comprehension difficulties at the ages of 8 and 9 years relative to TD controls though those of the children with dyslexia were mild (relative to TD controls, d = 0.51 at age 8, d = 0.60 at age 8); while the most severe problems were found in the comorbid dyslexia + DLD group (d = 1.79 at age 8, d = 2.06 at age 9) those with DLD also had significant difficulties (d = 1.56 at age 8, d = 1.56 at age 9).

CONCLUSIONS: These findings confirm that children with dyslexia or DLD are at-risk for reading comprehension difficulties but for different reasons, because of weak decoding in the case of dyslexia or weak oral language skills in the case of DLD. Different forms of intervention are required for these groups of children, targeted to their particular area(s) of weakness.

Original languageEnglish
Number of pages9
JournalJournal of Child Psychology & Psychiatry
Early online date20 Oct 2019
Publication statusE-pub ahead of print - 20 Oct 2019

Bibliographical note

© 2019 The Authors. Journal of Child Psychology and Psychiatry published by John Wiley & Sons Ltd on behalf of Association for Child and Adolescent Mental Health.

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